FEATURE — Hazards
Natural hazards differ from natural disasters in that “disasters” only affect humans. In the past year, humans have clashed with nature around the world: severe droughts in the American South; unprecedented heat waves and wildfires in Southern Europe; severe storms and floods in the American Midwest, Mexico, Northern Europe and much of Southeast Asia; landslides in the Pacific Northwest, California and Southeast Asia; devastating earthquakes in Indonesia; and typhoons in the Pacific, just to name a few. And climate change models predict that the intensity of storms, heat waves, droughts and related phenomena are only going to worsen over the coming decades.
However, an interesting trend is beginning to emerge, says Scott Burns, a geology professor at Portland State University in Oregon: “Man is beginning to work with Mother Nature instead of against her,” he says. Burns spoke with Geotimes managing editor Megan Sever about the new trend, what we’ve learned from 2005’s Hurricane Katrina and why houses just keep sliding down hillsides.
MS: What’s the biggest story this year? And what trends have we seen?
Katrina was a huge disaster two years ago that really affected us: We’re now looking at the quality of levees everywhere, because what caused most of the destruction in New Orleans was the levees breaking, causing a huge flood and really wreaking havoc. And it was poor quality in the construction of those levees, and not understanding the geology when they were built, that led to the destruction. All over the United States and around the world, that one event led us to say, “We need to check our levees.”
Another trend we’re seeing is that we continue to look at the quality of our dams, asking, “Are they going to hold up?” and figuring out what needs to be done to ensure they are safe. Another big deal is dam removal. This is a huge topic. It takes a vast amount of geology [to properly remove a dam], because you want to get the streams repaired so they can transport the fish. But you have all this sedimentation that has occurred behind the dams, so you have to figure out what to do with that. This is a complex issue.
Another major event that occurred this summer was the bridge that collapsed in Minnesota [in August]. That led immediately to everybody looking at their bridges, wondering if theirs were safe.
MS: The bridge collapse wasn’t geologic though. How are engineering geologists involved in such disasters?
MS: It seems like a lot of what we’re talking about is reparative work or reevaluations.
MS: There have been a number of landslides and debris flows this year, from California to the Pacific Northwest to Southeast Asia. Are such events increasing?
MS: So how can we plan for these events or mitigate the human impacts?
Also, cities and states need to work with engineering geologists to update their local ordinances — and that includes most of the hazards, your earthquakes, floods, landslides, etc. We’re trying to get more communities to upgrade their ordinances, and trying to get more geologists involved in that effort.
Another thing we’re trying to do is get more geology departments to teach applied geology. We need to get more young people coming out of departments where they can do applied geology — a field where there are lots of jobs.
The U.S. economy is doing well, so we’ve had this big housing boom and buildings are being put up everywhere. That’s going to lead to a lot of work for engineering geologists.
After each drought, heat wave or flood, talk abounds over whether the event was caused by global warming or natural variability — and, as a result, over what to do. In the past year, the discussion has focused increasingly on “geoengineering” Earth as a way to stop the effects of climate change — for example, blocking the sun, salting clouds to produce rain on command, or putting carbon dioxide into the ocean.
This fall, Geotimes managing editor Megan Sever spoke with Kevin Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research in Boulder, Colo., about the year’s main events and the prospect of geoengineering —a topic he and colleagues examined earlier this year in a paper in Geophysical Research Letters.
MS: It seems like there have been a lot of bad droughts and bad floods this year. Is this year anomalous? Or is it just that we’re now hyper-sensitive to this sort of thing?
In the tropics, there’s usually someplace that is dominant. In 2005, we had an extraordinary hurricane season in the Atlantic with Katrina and Rita and Wilma, and so on. Last year (2006), tropical storm activity was relatively weak in the Atlantic — or actually close to normal. And when there’s an El Niño event, as in 2006, there tends to be more action in the Pacific. And this year, the first part of the season (May to July), the action was much more in the Indian Ocean.
Overall, the hurricane season in the Atlantic has been about normal this year. The only thing that’s been exceptional is that two of the hurricanes were Category-5 storms. And the storms that made landfall in Texas had heavy rains associated with them, which produced tremendous flooding.
And over the summer, severe drought developed in the Southeast and California, with wildfires breaking out in California in October as a result.
It’s very likely that some of this is related to climate change.
MS: You beat me to my next question.
MS: Some scientists have said that they don’t yet have a grasp on hydrologic changes expected with climate change. Are we learning more about that?
Perhaps the bigger change is that more of the precipitation is occurring in heavy rainfall events. What’s happening is that the rising temperatures lead to increased evaporation, which puts more moisture in the atmosphere. And the fact that the atmosphere itself is warming up as well means that it can hold more water vapor. Basically, for every 1 degree Fahrenheit increase in the temperature, the atmosphere can hold about 4 percent more water vapor.
MS: Generally speaking, are extreme events expected to worsen with climate change?
This means that managing water resources is going to be more of a challenge. There are times when you don’t have enough water, and then there are times when you’ve got too much.
MS: What do you think is bringing geoengineering to the forefront?
MS: In your GRL paper, you studied the effects of Mount Pinatubo on the global hydrological cycle to see what the effects might be if we simulated a volcanic eruption, as a geoengineering ploy, to block out the sun to cool the planet. What did you find?
So people have been saying, “Maybe we can block out the sun in some fashion and cut down on warming.” This is not exactly the same as stopping the increases in the greenhouse effect, because increases in carbon dioxide in the atmosphere change the outgoing radiation on the planet, whereas if you block out the sun, by emulating a volcano or putting reflectors somewhere between the sun and Earth, then that cuts down the incoming solar radiation.
MS: Generally, do you think geoengineering is a good or bad idea?
But the other part of geoengineering is that once you start doing it, if you decide that it’s too expensive or that you can’t keep doing it, the downside of suddenly going back to the greenhouse world could be a lot worse than if you’d gradually let warming occur in the first place. I really think there’s a lot more we can do to address the real problem, in cutting back our emissions and cutting back our energy use before we really set on that path.